Category Archives: ecology

Aug 29 NO comments
agriculture, anthocyanins, Australia, Cabernet Sauvignon, ecology, economics, enology, fermentation, GPS, grapes, phenolics, prices, remote sensing, research, soil, Viticulture, wine chemistry, wine quality

Selective Harvesting: Is It Right For Everyone?



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When it comes to selective harvesting methods in the vineyard, there is an assumption that these methods may not be economically feasible for large quantity-producing wineries, as selective harvesting almost always requires more time, effort, and man-hours in executing.  Past research has found that the yield and quality of grapes is highly variable in the vineyard, which gives opportunity for winegrowers to better manage their resources and harvest practices for the desired quality of wine produced.

What is “Selective Harvesting”?

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Selective harvesting is defined as the split picking of fruit according to their yield and quality, in order to monopolize on a specific quality level in the grapes, and ultimately, finished wine.  This is sometimes achieved by sorting the grapes in the field into different bins depending on quality criteria, or by harvesting different sections of the vineyard at different times, again depending on quality criteria.  Studies have shown that grapes harvested from different portions of a vineyard may have significant chemical or sensory characteristics, which are often due to variations in the land and soil underneath the vineyard.

Selective harvesting may be problematic at times, as sometimes a winery may only have access to a single crusher or a minimum tank size of 75 tons, which can make separating grapes into two bins at harvest an issue, as well as filling a single tank with enough juice from a smaller selective harvest.  One study demonstrated that a 3 hectare low-yielding vineyard could not produce enough grapes to fill a fermentation tank with juice, which may make selective harvesting of smaller areas difficult when only certain sized tanks are available for use.

Perceptions of Selective Harvesting in Australia

In general, Australian wineries have the view that selective harvesting is only appropriate for small boutique wineries, or very large wineries that have access to a wide variety of equipment.  Those wineries in Australia’s inland warm irrigated region, according to the authors of the study presented to you today, are under the assumption that selective harvesting is not within reach.  It is because of this assumption that Bramley et al, 2011 sought to examine this assumption more closely, and to either support or refute the idea using field experimentation and economic analysis.

How did they do it?

The vineyard for this study was a Cabernet Sauvignon vineyard, planted in 1994, and located at the Deakin Estate in the Murray Valley of northwest Victoria, Australia.  Plant vigor and grape yield was calculated using remotely sensed digital multispectral video imagery, as well by using mechanical harvesters with GPS and Farmscan equipment.  Zones within the vineyard were characterized by being either high-yielding or low-yielding based on information gathered by the aforementioned methods.  After determining the yield would be too low for the fermentation tanks at the low-yield site, another low-yield site (harboring grapes with very similar characteristics as the grapes from the original low-yield site) from a Cabernet Sauvignon vineyard at Deakin Estate was also included in order to obtain the minimum yield necessary to fill the fermentation tanks available.

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Grapes were monitored throughout the growing season, and were harvested at 24 oBrix.  12 random bunches were collected from each zone in order to measure bunch weight, mean berry weight, juice Brix, pH, titratable acidity, anthocyanins (color), and phenolics.  Wines were created from bow low-yield zones and the high-yield zones in small-lot winemaking methods and also at the commercial scale.  For small-lot winemaking, 200kg of grapes were harvested then subsampled into three 50kg batches, and malolactic fermentation was not allowed to occur.  Commerical wines were made in 75 ton fermentation tanks which were filled for high-yield zone wines and filled only to 51 tons for the low-yield zone wines.  Malolactic fermentation was allowed to proceed for the commercial wines.  Standard winemaking procedures were used for all wines.

Experimental wines underwent a sensory analysis by 25 untrained panelists and Compusense Five (a sensory software tool).  For each comparison, the first sample presented was the reference sample, which was followed by two other samples, one of which was the same as the reference sample.  Panelists were asked to smell and taste the samples and to identify which sample was the same as the reference sample and were asked to provide the reason for their choice.

What did they find?

  • First and foremost, the authors noted a strong similarity between the remotely sensed data and the data collected from the GPS located on the harvesting machinery.  This provides evidence that the zones were actually separated properly into low-yield and high-yield zones. 


  • Wines created from the low-yield zone and wines created from a mix of low-yield zones were not significantly different, indicating that it was appropriate to mix the two low-yield sites without lowering the overall quality of the wine.


  • The wines from the high-yield zone tended to be more acidic and astringent than the wines from the low-yield zone.



  • When wines were made commercially, there was a significant different between wines made from high-yield zone grapes and wines made from low-yield zone grapes.  The low-yield zone grapes tended to be fuller bodied and less astringent, and with a fruitier aroma than the high-yield zone grapes.


  • Bunches from the high-yield zone were larger than those from the low-yield zone.  However, anthocyanin and phenolic concentrations were higher in wines made from low-yield zone grapes compared with high-yield zone grapes.  This result suggests greater wine quality in low-yield zone wines.


What do these results mean?

First, the results show that there are significant differences in yield and grape quality throughout different sections of a vineyard, which supports the need for purposeful zone delineation via posts, wires, or other means to separating sections of the vineyard.  Taking this one step further, another important result from the study is that if using remotely sensed data, it should be confirmed via ground-truthing (i.e. collecting information on the ground) to be certain the vineyard is being properly delineated.

The authors note that selective harvesting gives the winemaker greater control over the final blend of the wine, and ultimately the overall quality.  What many Australian winemakers are concerned about is the overall effect of cost when implementing such a strategy.  Even after taking in the harvest cost, the cost of small-lot winemaking, the harvest cost related to differing yield sizes, and total retail values (less expensive versus high-end prices), the researchers found that there was a total net benefit to a selective harvesting strategy.  See the table below (Table 2 from Bramley et al, 2011) for exact costs and benefits calculated.
Table 2 from Bramley et al, 2011

What about those vineyards that don’t make wine themselves?

There are many vineyards in Australia (and other places of the world, for that matter) that grow grapes to sell to other wineries, and not to make wine themselves.  Thereby, they do not have the added revenue of wine sold to add into the cost-benefit equation.  The authors were well aware of this fact, and performed a similar economic analysis to the one just mentioned, except leaving out the cost of winemaking and any potential wine revenue.  Even after taking these things into consideration, the researchers found that selective harvesting results in an increase in net financial benefit by more than 9% (in this particular example).  See the table below (Table 3 from Bramley et al, 2011) for exact costs and benefits calculated.

Table 3 from Bramley et al, 2011

Conclusions

The results of this study indicate that the notion that selective harvesting is only feasible for larger wineries with a variety of equipment sizes or small boutique wineries is incorrect, and that selecting harvesting may be financially feasible and beneficial for those wineries who undertake more large-scale production methods (at least in warm inland irrigated regions of Australia).  It is important to note that in order to maximize the benefit of selective harvesting, detailed analysis of the vineyard to delineate yield and quality zones must be confirmed using both remote sensing data and data collected directly from the ground.

Overall, I found this study interesting in that it showed that selective harvesting may be an option for all types of wineries, and is not limited to only those wineries with a greater variety of equipment or small boutique wineries.  One needs to remember, however, that this study occurred in a very specific wine region (warm inland irrigated region of Australia), the results of which may or may not be extrapolated to all wine regions around the world.  More research would need to be done to determine if this sort of harvest method is appropriate for wineries in any given wine region.

What do you all think of this topic?  If you’re curious to know more details about the methods or results of the study, please feel free to ask and I’ll see what I can find!

Please feel free to leave your comments below!

Reference:

Bramley, R.G.V., Ouzman, J., and Thornton, C. 2011. Selective harvesting is a feasible and profitable strategy even when grape and wine production is geared toward large fermentation volumes. Australian Journal of Grape and Wine Research 17: 298-305.

DOI: 10.1111/j.1755-0238.2011.00151.x
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Aug 02 NO comments
agriculture, anthocyanins, chemistry, contaminants, copper, ecology, environment, flavor, grapes, irrigation, phenolics, research, Viticulture, wine chemistry, wine quality, winemaking

The Effect of Irrigation on the Chemical Composition of Grapes



Every chemical compound in grapes and in wine play some role in the life of the grape/wine, be it during physiological processes during the growth stage, or in the finished wine itself, where it may contribute to the taste and flavor of the wine or the stability of the beverage over time.  For example, anthocyanins are responsible for the color of the grape berries, and ultimately for the finished wine.  Also, flavonols, while they are colorless in the skins of grapes, they are thought to act as a sort of shield against UV radiation.  The exact composition of these compounds in grapes and wine depend on a variety of factors, including grape variety/genetics, environmental factors, and viticulture and winemaking practices.  Studies have also suggested that anthocyanin and flavonol composition is a function of grape growth and skin characteristics.

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Most research to date has focused on the phenolic composition of grapes and wine, with very little focus on the many remaining chemical compounds in the fruit and finished beverage.  Phenolics should not be the only thing considered during these research studies, as there is likely a synergistic effect between multiple compounds in the system.  Understanding of the full chemical composition of grapes and wines are important not only from a purely scientific standpoint, but also for the grape grower and winemaker due to the direct effects on fruit and wine quality.

The goals of the study presented today were to determine the effect of irrigation management (a viticultural factor that may possibly alter the chemical composition of grapes/wine) on plant yield and physiology, as well as grape berry morphological characteristics, polyphenol and metal composition.  The study also sought to determine the absence of irrigation all together could have an effect on grape quality.

Methods

The experiment was performed in 2008 in a 5 year old vineyard in Montegiordano Marina, Southern Italy.  The climatic conditions there are considered “very hot” (climatic region 5).

The experimental vineyard plot was 0.3ha, with 10 rows of spur-pruned vines trained to a permanent horizontal unilateral cordon.  Distance between vines was 2.5m with 1m between rows.  Final plant density was 4000 vines per hectare.  Rows were planted in a north-south orientation.

Half of the plants were subject to irrigation from the early stages of fruit set to veraison using water amounts equal to 100% of cultural evapotranspiration.  Specifically, this equaled 24L per plant per each irrigation event (10 total) at 5 day intervals.  The other half of the plants were not subject to irrigation.

Meteorological variables that were measured or calculated were: temperature, rainfall, and photosynthetic photon flux density.  Physiological characteristics measured or calculated were leaf-to-air vapor pressure deficit, stem water potential (in order to determine plant water status), leaf gas exchange, chlorophyll florescence, basal florescence yield in dark-adapted leaves, maximal florescence yield in dark and light conditions, maximum quantum yield of PSII photochemistry in dark-adapted leaves, and finally the effective quantum yield of PSII in light-adapted leaves.

At harvest, 30 plants per treatment were randomly selected and the following were measured/calculated: number of clusters and yield per plant, cluster weight, number of berries per cluster, total berry weight per cluster, and the number of leaves per shoot.  For each plant, 3 clusters were randomly selected.

Berries from each cluster were separated into different weight categories: 1) less than 0.60g; 2) between 0.60 and 0.90g; 3) between 0.90 and 1.25g; and 4) greater than 1.25g.  For each plant, 20 grapes per weight class were randomly selected to measure/calculate berry fresh weight, berry diameter at the “equator”, and berry diameter at the “poles”.  The following characteristics were calculated for the berries: surface, volume, surface/volume ratio, the ratio of berry surface/berry weight, and the ratio of skin weight/berry weight.  Skin thickness and soluble solid content of berries was also measured.

For anthocyanin and flavonol extraction and analysis, three clusters per plant were randomly selected and berries separated into the aforementioned weight categories.  Anthocyanins and flavonols were measured, as well as levels of iron, copper, zinc, and calcium.

Results

(Note: I’m leaving out many exact details about values due to space limitations, but if you need to know exact numbers/values of any item presented in the results, just ask and I’ll see if those details are available and will let you know).

  • The growing season was marked with high temperatures and low rainfall.

o   Max temperatures ranged between 15.3 and 38.5oC.
o   Min temperatures ranged from 12.3 and 29.1oC.
o   Rainfall during the experimental growing season was a very low 21.9mm.
  •  There were no significant differences between irrigated and not irrigated plants in regards to net photosynthesis.
  • There were no significant differences in transpiration values between either of the treatments.
  • There were no significant differences in stomatal conductance between either of the treatments.
  • Maximum quantum yield of photosystem II and actual quantum yield of PSII reaction centers in leaves were not affected by irrigation treatment.
  • Mean numbers of clusters per plant were not different between treatment groups.
  • Yield per plant, cluster weight, and total berry weight were significantly different between treatment groups, with higher values occurring in the irrigation group.

o   Irrigation significantly increased the frequency of grapes with greater than 1.25g mass and reduced the frequency of grapes with less than 0.6g mass.
  • Irrigation treatment significantly affected berry fresh weight and skin fresh weight.

o   Irrigation significantly affected berry surface/volume ratios, and were significantly higher in irrigated plants.
o   Skin fresh weights were higher in non-irrigated plants, which resulted in a decrease in skin specific surface and increased in skin specific weight.
o   For the two intermediate weight categories, there were significant differences between the two treatment groups were noted for seed weight per berry as a result in the differences between seed number per berry.
§  There were more seeds in non-irrigated plants than in the irrigated treatment group.
  •  Soluble solid content was significantly higher in the non-irrigated group than the irrigated group.
  • Total anthocyanins were significantly higher in the non-irrigation group than the irrigation group.

o   This result was positively correlated with berry weight.
  • Significant differences were found in the concentrations of petunidin-3-O-acetylglucoside, peonidin-3-O-acteylglucoside, and petunidin-(6-O-caffeoyl)glucoside.

o   Levels were higher in non-irrigated plants (9x, 18x, and 10x, respectively).
  • Levels of single anthocyanins increased with decreasing berry weight.
  • Berries from irrigated plants had significantly lower ratios of acetylated anthocyanins/coumaroylated anthocyanins.
  • Total flavonols were not significantly different between the two treatment groups.

o   Levels of single flavonols were significantly higher in heavier berries.
  • Iron, copper, and zinc levels were significantly higher in berries from irrigated plants than from non-irrigated plants.
  • Calcium levels were not significantly different between the two treatment groups.
  • Metal levels significantly decreased in increasing berry weight.
  • There were no differences in berry skin thickness between either treatment group.
  •  No significant differences were found in the number of skin layers and thickness of the berries between either treatment group.


Conclusions

One undesired outcome of this experiment was the near drought-like conditions of the weather during the experiment.  This resulted in plants being subject to moderate-severe water stress, which caused some leaf necrosis and can influence the micro-climate at the cluster.  Specifically, it has been shown that this type of stress may affect berry size and chemical composition, thereby potentially changing the outcomes of some of the tests, and making it generally more difficult to tease out cause and effect.

The results of this study also showed that total anthocyanins were higher in grapes from non-irrigated plants than in irrigated plants.  This results in a positive influence on the long-term color stability of wines, as these compounds working in concert with tannins and flavonols to strengthen color stability in the aging beverage.  Additionally, increases in these compounds and well as the observed increases in petunidin-3-O-acetylglucoside and peonidin-3-O-acteylglucoside, can have positive sensory benefits to the finished wine as well.

Another interesting result from this study is that metal levels significantly decreased with increasing berry weight.  Excess metal concentrations in wine are known to cause negative sensory characteristics, delay the fermentation process, and increase instability.  Fe, Cu, and Zn were all found to be significantly lower in grapes from non-irrigated plants than in irrigated plants.

Overall, the results of this study suggest that less irrigation increased the quality of the finished wine.  Specifically, little to no irrigation results in lower berry yield and a reduction in berry size without negatively affecting grape quality in terms of the chemical composition of the grapes.  This study confirms what many in the wine industry in that grapes grown under water stress conditions can result in higher quality wine (provided there are no set-backs during the winemaking process).  Even though many already knew less water is better, this study paints a good picture of exactly how the chemical composition of the grapes changes when subject to these drier conditions.

There are many more results to this study that I did not cover due to time and space considerations, but I’d love to hear your thoughts or questions on them, even if I didn’t specifically cover it.  What do you all think of the study?  What would you like to have seen done differently (if anything).  I, for one, would have liked to see them create experimental wines from these two treatment groups and measure the same compounds to see how irrigation actually alters the chemical composition of the finished wine and not just the starting point grapes.  Do these differences carry through the winemaking process?  Are different winemaking techniques better suited to maintaining the original/similar chemical composition of the grapes?

I’d love to hear what you think! Please feel free to comment below!

Source: Sofo, A., Nuzzo, V., Tataranni, G., Manfra, M., De Nisco, M., and Scopa, A. 2012. Berry morphology and composition in irrigated and non-irrigated grapevine (Vitis vinifera L.). Journal of Plant Physiology 169: 1023-1031.

DOI: 10.1016/j.plph.2012.03.007



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 27 NO comments
agriculture, Cabernet Sauvignon, Chardonnay, ecology, environment, grapes, powdery mildew, research, Viticulture

Different Vineyard Training Systems Alter Susceptibility of Grapes to Powdery Mildew



One of the most common pests to vineyards all over the globe is powdery mildew (Erysiphe necator Schwein).  It is responsible for causing widespread destruction in nearly every viticultural area worldwide, and is a fungus that is able to develop in a variety of temperatures and humidity levels.  Though it is present in nearly every corner of the globe, the severity of the infection from vineyard to vineyard is dependent upon a variety of factors, including the variety of grape, the vigor of the vines, the type of protective chemicals applied, and the weather conditions.

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Some studies have found that the training system used in the vineyard has a significant effect on powdery mildew development, by altering the microclimate in the cluster area.  It appears as though light intensity and UV radiation appear to contribute to the changes in powdery mildew development severity, both of which have also been shown to affect the chemical composition of the grapes themselves.   Specifically, work done by the authors of the paper presented today found that there were significantly lower powdery mildew infections in grapes trained in the free canopy system versus grapes trained in the vertical shoot positioned system.

The article presented today is a very short article with the objective of investigating whether or not the difference in infection incidences as described above were due to light intensity itself, the susceptibility of the berries, or both.

Methods

The study was performed in June 2003 at an experimental vineyard in the Golan Region of Northern Israel.  Grapevines planted in this vineyard were Cabernet Sauvignon and Chardonnay (both with good susceptibility to powdery mildew).

Half of the vineyard was subject to a vertical positioned system, while the other half was left as a free canopy, though topped to one meter in length after fruit set and hedged no more than twice during the growing season.  Dates of bud burst, flowering, and fruit set were the same for both training systems.
Figure 1 from Zahavi and Reuveni, 2012

Experiment 1: Clusters were picked when the diameter of the berries were 3-5mm.  Thirty to forty berries from each training system were selected and placed in plastic boxes.  Berries were then inoculated with powdery mildew.  Twenty more berries were placed in plastic boxes but not inoculated with the fungus to serve as a control to monitor natural infections from the field.  Percent of infected berries was then calculated 7-9 days after inoculation with powdery mildew.

Experiment 2:  Clusters were inoculated in the exact same manner as in Experiment 1, however, 1-2 hours after inoculation, berries were returned to the vineyard and either placed on the cluster zone/vine cordon of their original training system or on vine cordon of the opposite training system for 8 hours.  After this time, berries were brought back to the laboratory and disease development was monitored 7-9 days after.

Results

  • For the first experiment, incidence of powdery mildew was significantly higher on berries originating from the vertical positioned vines than those originating from the free canopy system.
  •  For the second experiment, berries that originated from the vertical positioned vines and then incubated in those same vines were significantly more infected with powdery mildew than those berries that originated from the free canopy vines and incubated in either of the vine position systems.
  • Also in the second experiment, berries that originated from the vertical positioned vines that were incubated in the free canopy system vines had an intermediate level of powdery mildew disease severity.
  • Powdery mildew did not develop on control berries that were not inoculated.


Conclusions

The results of this study found that grapes originating from a free canopy system, which has a greater exposure to light, resulted in lower susceptibility to powdery mildew infection than grapes originating from vertically positioned vines, which have a denser canopy that does not allow in as much light. 

By transferring inoculated free canopy grapes into a vertical positioned set up, powdery mildew development decreased as a result of a pre-conditioning effect on the grapes.  In other words, this means that the grapes were less susceptible to infection after being exposed to higher intensity of light from the free canopy system.  The authors conclude by stating that the conditions in which grapes develop influence the severity of infection by powdery mildew.

Being a short experiment, there are certainly many more questions that these results raised which cannot be answered with the results found.  For example, how do the different training systems affect the chemical and sensory characteristics of the wine?  Are there any differences?  Since it appears grapes grown under a vertical positioned system are more susceptible to powdery mildew than grapes grown under a free canopy system, it suggests that perhaps there are some chemical defense changes within the plant, which may or may not affect the overall sensory characteristics of a wine made from those grapes.

Would the results be the same for each and every variety of grape out there?  Or are Cabernet Sauvignon and Chardonnay more susceptible to powdery mildew invasion under a vertical positioned system while say Riesling and Malbec are more susceptible under a different training system?  I would think it once again boils down to plant defensive chemistry, but we’d need some further studies examining many more grape varieties to be sure.

What about other training systems?  What is the “hierarchy of susceptibility” for powdery mildew in Vitis vinifera grapes? 

The results of this study are not to suggest that one should switch from a vertical positioned system to a free canopy, however without any extra chemical defense (fungicides, etc), it might be recommended that one reconsider the training system that is employed at one’s vineyard.  There are, of course, many other factors that any given training system will affect, thereby requiring one to weigh all the pros and cons before choosing any particular method.

I’d love to hear what you all think of this study!  What questions did this study raise for you?  Please feel free to comment below!

Source: Zahavi, T., and Reuveni, M. 2012. Effect of grapevine training systems on susceptibility of berries to infection by Erysiphe necator. European Journal of Plant Pathology 133: 511-515.

DOI: 10.1007/s10658-012-9938-z





I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 04 NO comments
anthocyanins, aroma, Cabernet Sauvignon, china, ecology, enology, environment, flavor, phenolics, resveratrol, wine, wine chemistry, wine quality

The Phenolic Composition of Cabernet Sauvignon Wines in China: Demonstrating Terroir Effects



Phenolic compounds, which are found in grapes, can significantly influence the aroma, flavor, mouthfeel, color, and overall quality of a wine.  These compounds are found naturally in grapes, however can also be synthesized throughout the fermentation and aging processes.  As a result of this, there are many factors that can influence the phenolic composition of a wine, including but not limited to; grape variety, environmental influences, and winemaking techniques.  For wines that are single variety based and not aged after fermentation, the phenolic composition of the wine is highly dependent upon the grape and the conditions in the vineyard. 

Specifically, this is what the term “terroir” embodies: it is the definition of the geographical and environmental origin of the grapes that include characteristics such as soil type, climate, and topography, and who all those things combine to affect the composition and quality of a wine.  Favorable terroir conditions can produce very high quality grapes, which is a critical starting point for a good wine.  By understanding how terroir affects the phenolic composition of grapes, vineyards managers or winegrowers will have a greater understanding of how to manage and maintain the grapevine that will produce high quality wines.

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There is a lot known about terroir effects on grapes and wine throughout many portions of the world, however, there is little known that specifically compares individual phenolic compounds of single varietal wines from different winemaking regions, and even less so known about these effects in the newer wine regions of China.

The wine regions of China are very ecologically diverse, considering they are spread all over the vast country.  The Yunnan Zone can be found at altitudes between 1900 and 2400m above sea level; the Gansu Qilian Zone is located next to a desert; the Ningxia Helan Zone is past the mountains; the Yantai Shandong Zone and Changli Hebei Zone are by the sea; and finally the Huailai Hebei Zone is located in a cooler climate.  It is because of these regional differences that there is great potential for regional terroir effects in wines produced from Chinese grapes. 

The goal of the study presented today was to analyze the differences in phenolic composition in Cabernet Sauvignon vines from different winegrowing regions in China.

Methods

 5 growing regions in China were studied: Deqin of Yunnan (YNDQ); Yuquanying of Ningxia (NXYQY); Yuma of Ningxia (NXYM); Qilian of Gansu (GSQL); Changli of Hebei (HBCL); and Yantai of Shandong (SDYT). 

Cabernet Sauvignon vines were studied, since they are easily found growing in all wine regions of China.  Grapes were harvested at their full-ripened state and were in strict accordance with local wine production technical rules.  Wines went through alcohol and malolactic fermentations, but did not age afterward. 

In each growing region, two to four wineries were chosen and about 1000mLof fresh wine from each winery was collected from at least two different fermentation processes.  To ensure only regional terroir characteristics were at play, all wines from each growing region were pooled.  Each wine sample was studied in triplicate.

Anthocyanin phenolics were analyzed, as well as non-anthocyanins including flavan-3-ols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids, and stilbenes.  Anthocyanins were quantified by using malvidin-3-O-glucoside as a standard, and flavanols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids and stilebenes were quantified by using catechin, quercetin, gallic acid, caffeic acid, and resveratrol, respectively.

Results

Anthocyanins

  • 24 anthocyanins were identified in Chinese Cabernet Sauvignon wines.

o   All 24 were found in each Chinese growing region studied.
  •  Wine from the YNDQ region had the highest levels of anthocyanins.
  • Wines from GSQL and NXYQY regions had significantly lower levels of anthocyanins (due to very low delphinidin derivatives).
  • Cyanidin-3-O-glucoside and peonidin-3-O-glucoside were 5 times higher in YNDQ wines than wines from any other region.
  • Wines from HBCL had the highest levels of malvidin-3-O-glucoside and malvindin-3-O-(6-O-acetyl)-glucoside.
  • There were significant differences in anthocyanin levels between wine regions in China.


Flavan-3-ols

  • 16 flavan-3-ols were found in wines from all Chinese growing regions studied.
  • SDYT region displayed the highest levels of flavan-3-ols.

o   Concentrations in this region were nearly double that of GSQL and YNDQ wines.
o   This region also showed the highest levels of gallocatechin and procyanidin dimers.
  •  Wines from GSQL and YNDQ had the lowest levels of total flavan-3-ols.
  • NXYM wines had the highest levels of epicatechin.

o   These levels were nearly 30 times greater than levels found in YNDQ wines.
  • The highest levels of catechin were found in YNDQ wines.
  • SDYT wines had the lowest levels of catechin.


Flavonols

  • 10 flavonols were found in Chinese wines from the growing regions of study.
  • Highest levels of flavonols were found in YNDQ wines.

o   These levels were nearly 4 times greater than levels found in GSQL wines.
  • YNDQ wines had much higher levels of quercetin derivatives than wines made from other wine regions in China.
  • Higher kaempferol levels were found in NXYM wines.
  • YNDQ wines had the highest levels of dihydroquercentin-O-hexoside, while GSQL wines had the lowest levels.
  • YNDQ wines had higher levels of dihydroquercentin-O-rhamnoside, quercentin-3-O-glucuronide, and myricetin compared to all other regions.
  • Wines from NXYM and YNDQ had higher levels of kaempferol-3-O-glucoside than all other regions.

o   These values were double those found in GSQL and HBCL wines.

Hydroxybenzoic Acids

  •  3 hydroxybenzoic acids were found in Chinese wines.
  • Highest levels of total hydroxybenzoic acids were found in SDYT wines, and the lowest levels in NXYM wines.
  • SDYT wines had significantly higher levels of gallic acid, while NXYM wines had the lowest levels.


Hydroxycinnamic Acids

  • 4 hydroxycinnamic acids were found in Chinese wines.
  • GSQL and NXYQY wines showed the highest levels of total hydroxycinnamic acids.

o   These levels were nearly 5 times more than levels found in YNDQ wines.
  • GSQL wines had nearly 9 times more caffeic acid than YNDQ wines and 5 times more ethyl ρ-coumarate than wines made from NXYM and NXYQY grapes.
  • All wines had the highest percentage of gallic acid to total hydroxycinnamic acids.


Stilbenes

  • SDYT had the highest levels of stilbenes, while YNDQ wines had the lowest levels.
  • Trans-resveratrol was the most abundant stilbene in all wines, though was significantly variable between regions.

o   SDYT wines had nearly 7 times more trans-resveratrol than YNDQ wines.

Regional Similarities

  •  Cluster analysis revealed that wines from the Helan mountain of Ning-Xia (NXYM, NXYQY) and GSQL regions were similar in regards to their phenolic composition.
  • Wines from HBCL and SDYT regions were similar in regards to their phenolic composition.
  • The YNDQ wines were different in regards to their phenolic composition than from all other regions.


Conclusions

According to the results of this study, the differences in phenolic composition of Chinese wines in this study indicate that the accumulation of phenolic compounds in grapes is strongly influenced by terroir effects.  Going further, those regions that were geographically closer to one another had wines that were statistically similar to one another in regards to their phenolic composition than regions that were geographically isolated or further away.  NXYQY, NXYM, and GSQL, all of which were similar in phenolic composition, are all located in the drier area of Western China with a cool-warm climate.  HBCL and SDYT were found to be statistically similar to each other in regards to the phenolic content of wines, and were both located in the wetter areas of Eastern China with a warm climate.  Finally, YNDQ was found to be different from all other regions in regards to phenolic composition of wine, and was located on the plateau valley zone of Southwest China with a warm-arid climate.

Overall, these results clearly show terroir effects, and confirm that different regions in China, like other regions around the world, produce grapes that result in wines with statistically different phenolic compositions.  Terroir effects were found to be similar for wines from the Helan mountain of Ningxia and Qilian of Gansu; for wines from Changli of Hebei and the Yantai of Shandong; and finally with the wines from the Deqin of Yunan having significantly different terroir effects from all other regions.

This knowledge of terroir effects in China should give viticulturalists and winegrowers the knowledge necessary for maintaining and caring for vines from each particular region, as well as giving the winemakers knowledge necessary for creating a high quality wine made from grapes with very specific phenolic profiles.  By applying the knowledge gained from this study, grape growing practices and winemaking techniques may be adjusted accordingly in order to optimize wine flavor/aroma quality in China, at the very least with Cabernet Sauvignon grapes.

I’d love to hear what you all think of this topic!  Please feel free to comment below (any unauthorized html tags will be promptly removed).

Source: Li, Z., Pan, Q., Jin, Z., Mu, L., and Duan, C. 2011. Comparison on phenolic compounds in Vitis vinifera cv. Cabernet Sauvignon wines from five wine-growing regions in China. Food Chemistry 125: 77-83.

DOI:  10.1016/j.foodchem.2010.08.039



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jun 07 NO comments
agriculture, ecology, environment, Flavescence doree, grapes, insects, Italy, leafhoppers, organic, research, Viticulture

Put the Barry White on Pause: Using Vibrational Disruption as an Alternative to Chemical Pesticides in Vineyard Pest Management Practices



For commercial vineyards, and commercial agricultural farms in general, pest management employs the use of chemical pesticides.  These chemicals act to disrupt the communication between male and female insects that use sex pheromones to attract one another for mating.  However, there are many insects such as leafhoppers and plant-hoppers that do not use long range chemical pheromones, but instead utilizes vibrational signals to attract their mates.  Therefore, for these types of insects, there may be other pest management solutions that are less invasive and detrimental to the environment as the use of chemical pesticides.

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Insects can be the vector for many different plant diseases, including the leafhopper Scaphoideus titanus Ball, which is a vector for the grapevine disease Flavescence dorée.  This disease is lethal to the grapevine, and in Europe (among other places) it is a quarantine disease, which often employs the use of large-scale chemical insecticides for treatment.  In regards to communication, S. titanus males use vibrational signals to attach mating females.  It was the goal of the study presented today, to take this knowledge of the breeding patterns of S. titanus and test mating disruption based on substrate vibrations, in order to potentially find an alternative to the more toxic pesticide pest management methods.

Methods

S. titanus eggs were collects from organic farms in Villazzano in Trento, Italy.  The adults reared from these eggs were used in both semi-field and field experiments.  All leafhoppers used in the experiments were sexually mature adults that were at least 8 or exactly 10 days old.

A S. titanus male calling song was recorded using a laser vibrometer in a laboratory setting with the male singing 0.5cm from the “microphone”.

For the semi-field experiment, measurements occurred outdoors at Pisa University in Italy during July of 2010.  Five potted grapevines were pruned to be similar morphologically to a height of 70-75cm, two main branches, and 8 fully developed leaves.  A metal wire was used to fix the plants in an upright position, similar to how wires are situated in the vineyards.  Plants were placed in a row and about 190cm between each plant. 

An electromagnetic shaker was placed on the end of the row, resulting in varying distances between it and each plant (180cm, 370cm, 560cm, 750cm, and 940cm).  The shaker was activated using a laptop computer with Adobe Audition software with the amplitude of naturally occurring disturbance noise amplified 20 times.  The male calling song was applied to the leaf via the lamina of the upper leave by a comical rod attached to a mini shaker.  The amplitude was adjusted to the level of naturally occurring male calling songs.

To measure signal transmission through the plant, pieces of small square reflective tape were placed along the leaves and the stems, in order to focus a laser beam.  The vibrational signals were recorded using a laser vibrometer and digitized with a 48kHz sample rate and 16-bit resolution.  Intensity was measured as the maximum substrate velocity (mm/s).

Both male calling songs and disturbance noise were played back three times for each measuring point on each plant.  Velocity was measured for the three pulses with the highest amplitude to obtain an average velocity for 9 pulses per plant.  Average velocity was calculated across the three plants for all points from not only the leaf that incurred direct vibration, but also all other leaves.

Mating experiments were performed in July and August of 2010.  In addition to the vibrational plants, two plants that did not receive vibrational treatments were used as controls.  Each experimental plant was isolated in a transparent polyester cage that had closable openings in order to release and collect insects.

Field experiments were conducted at a vineyard at Fondazione Edmund Mach in Italy during July and August of 2011.  Mature plants at a height of 1.5m were grown in rows with each plant 70cm from one another.  An MP3-drive electromagnetic shaker was used to create both male calling songs and disturbance noise.  The shaker was attached to the wire on the vines, and was located 100, 310, 520, 730, and 940cm from experimental plants.

The shoot from the middle part of each plant was isolated in nylon netting, with closable openings in order to release and collect insects.

All experiments were conducted between 5pm and 10am the next day, since S. titanus making rituals occur during twilight or overnight.  Insects were recollected at 10am the next day.

For each overnight trial used one virgin male and female, that were both placed on separate leaves of each plant.  After recollecting the insects the next morning, females were isolated and dissected 10 days after isolation.  Differences between mated and unmated females were determined.  All females with 0-6 eggs were labeled as “virgin”, and all females with greater than 10 eggs were labeled as “mated”.  Any female with 7 to 9 eggs were too uncertain to remain in the study and thus data were removed.

Results

  •       The highest intensities of male calling signal were measured on the leaf that was vibrated on with the recorded songs.
  •        Disruptive vibrational signals masked male calling signals at all measured points.
  •       There was a significant difference in the number of virgin females between vibrated on and control plants.

o   There were no differences between vibrated plants at different distances from the recorded calling source.

Conclusions

The results of this short study, according to the authors, provide evidence that mating call disruption is an effective and environmentally friendly approach toward pest management in vineyards.  The disruptive noise covered over the male calling signal enough that there were significantly more virgin females in those plants exposed to the noise than those control plants that were not exposed.

Of course, insects were not completed eradicated from the system; however, it is possible that with the vibrational disruptive technique, populations could be kept at a more manageable level that is below the threshold for economic damage/loss.  This type of pest management may not only be successful in keeping populations of S. titanus in check, but may also be an important pest management method for other insects that also use similar vibrational mating rituals.  Of course, each individual species of insect would need to be studied, in order to determine the precise disruptive noise pattern that would be most successful in preventing mating events.

In summary, though this research is still in its infancy and much more work needs to be done, this method of vibrational disruptive noise applied to grapevine leaves may serve as an efficient and environmentally friendly approach to pest management in vineyards.

I’d love to hear what you all think about this topic!  Please feel free to comment below (please no HTML tags.  Any unapproved HTML tags posted will be deleted).

Source:  Eriksson, A., Anfora, G., Lucchi, A., Lanzo, F., Virant-Doberlet, M., and Mazzoni, V. 2012. Exploitation of Insect Vibrational Signals Reveals a New Method of Pest Management. PLoS ONE 7(3): e32954.

DOI: 10.1371/journal.pone.0032954



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!